Have you checked on iTunes? I've bought a lot of Irish (if that's what you mean by Celtic - is it?) stuff there.

Yes, I said I did in the original post.   iTunes, Amazon, Rhapsody, etc, mostly carry major bands with widespread label distribution.    As I said in my OP, O'Donovan goes over to Ireland and Scotland and brings back lots of CD's by bands that never get over here and they're great, and they sell CD's on their websites for more than I can afford.

My wife and I were in Scotland a few years ago and noticed the same thing - there are lots of great local bands no one on this side of the pond has ever heard of.

BTW - another advantage of selling electronically is this: once you do a pressing for X number of CD's, if you sell out but you don't think there'll be enough NEW sales to justify another run, then the CD is out of print.    That's why there is so much good music that's out of print. But you never "run out of electrons". If you project you're going to sell 1000 CD's so you press that many, and only 600 sell, you're stuck with 400 coasters that you paid for. If sell all 1000 and there's another 133 people who want to buy some, you can't sell any without taking the risk of another pressing batch.   Electronic distribution scales exactly to demand.